Semiconductor structure for isolation of semiconductor devices

Abstract

In an integrated circuit, particularly an integrated circuit for radio frequency applications, a semiconductor structure for isolation of semiconductor devices that includes a semiconductor substrate, at least one shallow trench extending vertically into the substrate, a deep trench laterally located within the shallow trench, where the deep trench extends vertically further into the substrate. The deep trench is self aligned to the shallow trench with a controlled lateral distance between an edge of the shallow trench and an edge of the deep trench and the lateral extensions of the shallow and deep trenches, respectively, are independently chosen.

What is claimed is:  
     
       1. In an integrated circuit, particularly an integrated circuit for radio frequency applications, a semiconductor structure for isolation of semiconductor devices comprised in said circuit, wherein said semiconductor structure comprises 
       a semiconductor substrate;  
       at least one shallow trench extending vertically into said substrate;  
       a deep trench laterally located within said shallow trench, said deep trench extending vertically further into said substrate, wherein  
       said deep trench is self aligned to said shallow trench with a controlled lateral distance between an edge of the shallow trench and an edge of the deep trench;  
       and the lateral extensions of the shallow and deep trenches respectively, are independently chosen.  
     
     
       2. The semiconductor structure of  claim 1  wherein said deep trench is asymmetrically located with respect to said shallow trench. 
     
     
       3. The semiconductor structure as claimed in  claim 1 , wherein said controlled lateral distance between an edge of the shallow trench and an edge of the deep trench is between 1000 and 4000 Å; 
       said lateral extension of said deep trench is about 1 μm or less; and  
       said lateral extension of said shallow trench is considerably larger than said lateral extension of said deep trench, said lateral extensions being oriented in the same direction.  
     
     
       4. The semiconductor structure as claimed in  claim 1 , wherein said semiconductor structure comprises a second deep trench located laterally within said shallow trench, said second deep trench extending vertically into said substrate further than said shallow trench, and said second deep trench being self aligned to said shallow trench. 
     
     
       5. The semiconductor structure as claimed in  claim 1 , wherein said controlled lateral distance between an edge of the shallow trench and an edge of the deep trench is set by a thickness of a conformally deposited dielectric layer during manufacture of the semiconductor structure. 
     
     
       6. The semiconductor structure as claimed in  claim 1 , wherein said at least one shallow trench and said deep trench are etched structures. 
     
     
       7. The semiconductor structure as claimed in  claim 6 , wherein said at least one shallow trench and said deep trench are provided with an oxide liner on their bottoms and sidewalls. 
     
     
       8. The semiconductor structure as claimed in  claim 7 , wherein said at least one shallow trench and said deep trench are provided with an isolation layer on top of said oxide liner. 
     
     
       9. The semiconductor structure as claimed in  claim 8 , wherein said isolation layer is TEOS layer. 
     
     
       10. The semiconductor structure as claimed is  claim 6 , wherein said at least one shallow trench and said deep trench are filled with semiconducting or insulating material. 
     
     
       11. The semiconductor structure as claimed in  claim 10 , wherein the upper surface of said semiconducting or insulating filling material is planarized. 
     
     
       12. The semiconductor structure as claimed in  claim 1 , wherein said semiconductor substrate is of silicon. 
     
     
       13. The semiconductor structure as claimed in  claim 1 , wherein said at least one shallow trench extends vertically into said substrate to a depth which is larger than said controlled lateral distance between an edge of the shallow trench and an edge of the deep trench. 
     
     
       14. The semiconductor structure as claimed in  claim 1 , wherein said at least one shallow trench extends vertically into said substrate to a depth of 0.2-0.7 μm. 
     
     
       15. The semiconductor structure as claimed in  claim 1 , wherein said deep trench extends vertically into said substrate to a depth of at least a few microns. 
     
     
       16. In an integrated circuit, particularly an integrated circuit for radio frequency applications, a semiconductor structure for isolation of semiconductor devices comprised in said circuit, wherein said semiconductor structure comprises 
       a semiconductor substrate;  
       at least one shallow trench extending vertically into said substrate;  
       a deep trench located laterally within said shallow trench, said deep trench extending vertically further into said substrate, wherein  
       said deep trench is self aligned to said shallow trench with a controlled lateral distance between an edge of the shallow trench and an edge of the deep trench;  
       the lateral extensions of the shallow and deep trenches, respectively, are independently chosen; and  
       said semiconductor structure comprises a second deep trench located laterally within said shallow trench, said second deep trench extending vertically into said substrate further than said shallow trench.  
     
     
       17. The semiconductor structure as claimed in  claim 16 , wherein said second deep trench is self aligned to said shallow trench. 
     
     
       18. The semiconductor structure as claimed in  claim 16 , wherein said controlled lateral distance between an edge of the shallow trench and an edge of the deep trench is between 1000 and 4000 Å said lateral extension of said deep trench is about 1 μm or less; and said lateral extension of said shallow trench is larger, preferably considerably larger, than said lateral extension of said deep trench, said lateral extensions being oriented in the same direction. 
     
     
       19. In an integrated circuit, particularly an integrated circuit for radio frequency applications, a semiconductor structure for isolation of semiconductor devices comprised in said circuit, wherein said semiconductor structure comprises 
       a semiconductor substrate;  
       at least one shallow trench extending vertically into said substrate;  
       a deep trench laterally located within said shallow trench, said deep trench extending vertically further into said substrate, wherein:  
       said deep trench is self aligned to said shallow trench with a controlled lateral distance between an edge of the shallow trench and an edge of the deep trench,  
       the lateral extensions of the shallow and deep trenches respectively, are independently chosen, and said controlled lateral distance between an edge of the shallow trench and an edge of the deep trench is between 1000 and 4000 Å.  
     
     
       20. The semiconductor structure as claimed in  claim 19 , wherein said lateral extension of said deep trench is about 1 μm or less.